int ledPin = 13;                // choose the pin for the LED
int inputPin = 2;               // choose the input pin (for a pushbutton) 按键接到数字2
int val = 0;                    // variable for reading the pin status
void setup()
{
  pinMode(ledPin, OUTPUT);      // declare LED as output
  pinMode(inputPin, INPUT);     // declare pushbutton as input
}
void loop()
{
  val = digitalRead(inputPin);  // read input value
  if(val == HIGH)
  {        
     // check if the input is HIGH
     digitalWrite(ledPin, LOW);  // turn LED OFF
  }
  else
  {
     digitalWrite(ledPin, HIGH); // turn LED ON
  }
}

